One of three surfaces is produced by a complete second-order model with two quantitative
independent variables: a paraboloid that opens upward, a paraboloid that opens downward, or a
saddle-shaped surface.

Question

Quizplus · Accepted Answer

A complete second-order model with two quantitative independent variables can indeed produce one of three types of surfaces: a paraboloid that opens upward, a paraboloid that opens downward, or a saddle-shaped surface, depending on the signs and magnitudes of the coefficients in the model.

One of Three Surfaces Is Produced by a Complete Second-Order